def test_slice_stride(self):
a = b'World_ _i_s_ _hell!'
a_refcount = sys.getrefcount(a)
b = containers.ArrayView(a)
b_refcount = sys.getrefcount(b)
self.assertEqual(sys.getrefcount(a), a_refcount + 1)
# When slicing to a strided array view, b's refcount should not change
# but a's refcount should increase. Check consistency with slices on
# bytes, slicing bytes will make a copy so it doesn't affect the
# refcount.
c1 = a[4:-4:2]
c2 = b[4:-4:2]
self.assertIsInstance(c2, containers.StridedArrayView1D)
self.assertEqual(len(c1), 6)
self.assertEqual(len(c2), 6)
self.assertEqual(bytes(c1), b'd is h')
self.assertEqual(bytes(c2), b'd is h')
self.assertEqual(c2.size, (6, ))
self.assertEqual(c2.stride, (2, ))
self.assertEqual(sys.getrefcount(b), b_refcount)
self.assertEqual(sys.getrefcount(a), a_refcount + 2)
# Deleting a slice should reduce a's refcount again, keep b's unchanged
del c2
self.assertEqual(sys.getrefcount(b), b_refcount)
self.assertEqual(sys.getrefcount(a), a_refcount + 1)
def test_init_buffer_memoryview_obj(self):
a = b'hello'
v = memoryview(a)
b = containers.ArrayView(v)
# memoryview's buffer protocol returns itself, not the underlying
# bytes, as it manages the Py_buffer instance. So this is expected.
self.assertIs(b.owner, v)
def test_init_buffer(self):
a = b'hello'
a_refcount = sys.getrefcount(a)
b = containers.ArrayView(a)
self.assertIs(b.owner, a)
self.assertEqual(len(b), 5)
self.assertEqual(bytes(b), b'hello')
self.assertEqual(b[2], 'l')
self.assertEqual(sys.getrefcount(a), a_refcount + 1)
# Not mutable
with self.assertRaisesRegex(TypeError,
"object does not support item assignment"):
b[4] = '!'
# b should keep a reference to a, so deleting the local reference
# shouldn't affect it
del a
self.assertTrue(sys.getrefcount(b.owner), a_refcount)
self.assertEqual(b[2], 'l')
# Now, if we delete b, a should not be referenced by anything anymore
a = b.owner
del b
self.assertTrue(sys.getrefcount(a), a_refcount)
def test_init_buffer_empty(self):
a = b''
a_refcount = sys.getrefcount(a)
b = containers.ArrayView(a)
self.assertIs(b.owner, None)
self.assertEqual(len(b), 0)
self.assertEqual(sys.getrefcount(a), a_refcount)
def test_init_buffer_unexpected_stride(self):
a = memoryview(b'hello')[::2]
self.assertEqual(bytes(a), b'hlo')
# Error emitted by memoryview, not us
with self.assertRaisesRegex(
BufferError,
"memoryview: underlying buffer is not C-contiguous"):
b = containers.ArrayView(a)
def test_init(self):
a = containers.ArrayView()
b = containers.MutableArrayView()
self.assertIs(a.owner, None)
self.assertIs(b.owner, None)
self.assertEqual(len(a), 0)
self.assertEqual(len(b), 0)
self.assertEqual(bytes(a), b'')
self.assertEqual(bytes(b), b'')
def test_slice_stride_empty(self):
data = b'hello'
data_refcount = sys.getrefcount(data)
# slice.start = slice.stop
a = containers.ArrayView(data)[7:8:2]
self.assertEqual(len(a), 0)
# Empty view, original data not referenced at all
self.assertIs(a.owner, None)
self.assertEqual(sys.getrefcount(data), data_refcount)
def test_slice_stride_negative(self):
a = b'World_ _i_s_ _hell!'
b = containers.ArrayView(a)
# Check consistency with slices on bytes
c1 = a[-5:3:-2] # like [4:-4:2] above, but reverted
c2 = b[-5:3:-2]
self.assertEqual(len(c1), 6)
self.assertEqual(len(c2), 6)
self.assertEqual(bytes(c1), b'h si d') # like b'd is h' but reverted
self.assertEqual(bytes(c2), b'h si d')
self.assertEqual(c2.size, (6, ))
self.assertEqual(c2.stride, (-2, ))
def test_slice(self):
a = b'World is hell!'
a_refcount = sys.getrefcount(a)
b = containers.ArrayView(a)
b_refcount = sys.getrefcount(b)
self.assertEqual(sys.getrefcount(a), a_refcount + 1)
# When slicing, b's refcount should not change but a's refcount should
# increase
c = b[4:-4]
self.assertIsInstance(c, containers.ArrayView)
self.assertEqual(bytes(c), b'd is h')
self.assertEqual(sys.getrefcount(b), b_refcount)
self.assertEqual(sys.getrefcount(a), a_refcount + 2)
# Deleting a slice should reduce a's refcount again, keep b's unchanged
del c
self.assertEqual(sys.getrefcount(b), b_refcount)
self.assertEqual(sys.getrefcount(a), a_refcount + 1)
def test_convert_memoryview(self):
a = b'World is hell!'
a_refcount = sys.getrefcount(a)
b = containers.ArrayView(a)
b_refcount = sys.getrefcount(b)
self.assertEqual(sys.getrefcount(a), a_refcount + 1)
c = memoryview(b)
# Unlike slicing, ArrayView's buffer protocol returns a reference to
# itself -- it needs to be kept around because the Py_buffer refers to
# its internals for size. Also returning a reference to the underlying
# buffer would mean the underlying buffer's releasebuffer function gets
# called instead of ours which is *not* wanted.
self.assertIs(c.obj, b)
self.assertEqual(sys.getrefcount(b), b_refcount + 1)
self.assertEqual(sys.getrefcount(a), a_refcount + 1)
with self.assertRaisesRegex(TypeError, "cannot modify read-only memory"):
c[-1] = ord('?')
def test_init_array(self):
a = array.array('f', [1.0, 4.5, 7.9])
b = containers.ArrayView(a)
self.assertIs(b.owner, a)
self.assertEqual(len(b), 3 * 4)
def test_slice_stride_reverse(self):
# slice.stop = -1
a = containers.ArrayView(b'hello')[::-1]
self.assertEqual(len(a), 5)
self.assertEqual(bytes(a), b'olleh')
def test_slice_invalid(self):
with self.assertRaisesRegex(ValueError, "slice step cannot be zero"):
containers.ArrayView()[::0]
def test_slice_empty(self):
# slice.start = slice.stop
a = containers.ArrayView(b'hello')[7:8]
self.assertEqual(len(a), 0)
